1. Field of the Invention
The present invention relates generally to an automatic transmission primarily intended for motor vehicle use, and more particularly to, a noise control device for a solenoid-actuated valve in or connected to a transmission that is controlled electronically and hydraulically.
2. Description of Related Art
In an automatic transmission, hydraulic controls such as valves are used for applying and releasing elements to shift the gears of the transmission. The control system of the automatic transmission includes electrically operated solenoid-actuated valves for controlling certain fluid pressures. This hydraulic pressure control will cause either the actuation or deactuation of the respective applying and releasing elements for effecting gear changes in the transmission.
An example of a previous noise control device for a solenoid-actuated valve is disclosed in copending patent application, U.S. Ser. No. 188,618, filed Apr. 29, 1988, entitled "Noise Control Device for a Solenoid-Actuated Valve", which is hereby incorporated by reference. This device provided a spool slideably disposed in a passageway and having an axially projecting portion which contacts a ball of a valve. A spring is disposed in the passageway and biases the spool toward the ball such that it contacts its normal, deactivated seat. The spool also includes lands which allow only gradual flow of fluid past the spool to reduce or slow its pull in velocity and thus reduce impact noise between the ball and its active, energized seat.
3. Objects of the Present Invention
It is one of the principle objects of the present invention to provide a noise control device for a solenoid-actuated valve of an automatic transmission which is controlled electronically and hydraulically.
It is a more specific object of the present invention to provide a thermally compensated noise control device for a solenoid-actuated valve which reduces impact noise upon actuation of the solenoid-actuated valve.